An internal combustion diesel engine cylinder head of interest is disclosed in U.S. Pat. No. 4,860,700 to Smith, issued on Aug. 29, 1989 and assigned to the assignee of the present patent application, wherein the entire disclosure of said U.S. Pat. No. 4,860,700 is hereby herein incorporated by reference. In that the present invention is an improvement to the diesel engine cylinder head disclosed in said U.S. Pat. No. 4,860,700, a description of the disclosure thereof is generally presented hereinbelow with attention being directed to FIGS. 1 through 8.
Referring now to the drawings, the diesel engine cylinder head of U.S. Pat. No. 4,860,700 will be generally described. Numeral 10 generally indicates a cylinder head of the general type shown in U.S. Pat. No. 3,377,996 Kotlin et al, but having significant differences in the cooling water jacket structure as will be subsequently more fully described. The cylinder head embodiment disclosed when assembled with the usual valve mechanism, not shown, is primarily intended for use in a uniflow scavenged two-cycle engine of the fuel injection compression ignition type and is adapted to be secured in end sealing engagement to the upper end of a jacketed liquid cooled cylinder liner and to be mounted therewith in a cylinder mounting bore of an engine frame member wherein the cylinder head 10 cooperates with a piston reciprocably mounted in the liner to define an expansible combustion chamber therebetween.
The cylinder head 10 comprises a lower combustion chamber defining fire-face wall 12 engageable outwardly with the upper end of the associated jacketed liner. An upper head wall 14 extends in spaced parallel relation to the fire-face wall 12 and is connected thereto by a peripheral boundary sidewall 16. A flange 18 is coextensive with and extends upwardly and outwardly of the upper head wall 14 and the sidewall 16 to provide an annular shoulder 20. In mounting the cylinder assembly, this flange defined shoulder of the cylinder head is engageable with a mating shoulder provided therefor in the engine frame.
The sidewall 16 and flange 18 are structurally reinforced by a plurality of spaced vertically extending stud bosses 22, 23, 24, 25, 26, 27, 28 and 29. The stud bosses 22–29 define a plurality of stud holes 30 which are adapted to receive therethrough studs for securing the cylinder head to the jacketed cylinder liner. The upper head wall and fire-face wall are interconnected centrally of the cylinder head by a sleeve defining wall portion 32. The sleeve defining wall portion 32 provides a central opening 33 extending through the cylinder head which is of stepped and tapered diameters and is adapted to mount a suitable fuel injection device.
Four valve seat defining exhaust ports 34 extend through the fire-face 12 of the head in equispaced relation about the sleeve defining wall portion 32. The exhaust ports 34 communicate upwardly through short branch passages 35, 36, 37 and 38 with a common exhaust passage or chamber 39. The branch passages are defined by exhaust port wall portions 41, 42, 43 and 44 which extend upwardly between the fire-face wall 12 and a horizontal chamber wall 45. The chamber wall 45 extends inwardly from the sidewall 16 in spaced parallel relation above the fire-face wall 12, wherein an inner chamber wall surface 45a thereof faces an inner fire-face wall surface 12a of the fire-face wall, and terminates inwardly at its intersection with the sleeve defining wall portion 32. Four webs or partition walls 46 are provided extending vertically between the fire-face wall 12 and the chamber wall 45 and laterally between each of the exhaust port wall portions 41, 42, 43, 44 and the adjacent stud bosses 23, 24, 27 and 28, respectively, which connect with the sidewall 16
The exhaust passage 39 is defined between the chamber wall 45 and an upper passage wall 47. The upper passage wall 47 is structurally connected to the upper head wall 14 by four tubular or cylindrical wall portions 48 which extend therebetween in axial alignment with the several valve seating ports 34 and define bores 49 adapted to receive suitable valve guide bushings.
As is best seen in FIGS. 2 and 5, the exhaust passage 39 extends arcuately of the head, partially embracing the sleeve defining wall portion in spaced relation thereto and intersecting the several valve controllable branch passages 35–38, and communicates laterally outwardly with an exhaust outlet port 50 opening through the sidewall 16 of the head. The outlet port 50 is connectable to an exhaust manifold through a suitable branch passage which may be provided in the engine frame. The outlet port is vertically intersected by two struts 51 and 52. These struts are co-extensive with stud bosses 22 and 29 respectively and each has a passage 54 extending therethrough. The passages 54 permit the circulation of a coolant (i.e., cooling fluid) through the gas exposed struts 51 and 52.
It will be seen that the chamber and exhaust passage defining walls cooperate with the outer walls of the cylinder head to define a coolant-receiving compartment. This compartment is divided by the horizontal chamber wall 45 into a lower jacket chamber 55 and an upper jacket chamber 56. The lower jacket chamber 55 is divided by the partition walls 46 into four sections 58, 59, 60 and 61 which are alternately outlet and inlet sections that are interconnected by restricted passages 62 formed between the exhaust port wall portions 41, 42, 43 and 44 and the sleeve defining wall portion 32.
The upper and lower jacket chambers are interconnected through various openings in chamber wall 45 adjacent the inner periphery of sidewall 16. The primary connection is through a pair of relatively large passages 64 extending from the outlet sections 58 and 60 of the lower chamber upwardly past the upper exhaust passage wall 47 to the upper chamber. The chambers are also connected through four small openings or coolant by-pass ports 65 connecting with inlet section 59 and passages 54 in struts 51 and 52 which connect with inlet section 61 of the lower chamber.
The coolant is forced or drawn upwardly into the cylinder head through twelve inlet ports extending through and spaced around the fire-face wall 12 adjacent sidewall 16. Eight of these are relatively large coolant inlet ports 66 which open into inlet sections 59 and 61 of the lower chamber while four are relatively small coolant inlet ports 68 opening into outlet sections 58 and 60 of the lower chamber. The coolant inlet ports 66 and 68 mate with corresponding coolant ports provided in the jacketed cylinder liner structure which is connected in a conventional manner to the discharge of a coolant circulation pump. As shown in FIG. 1, the upper flange portion 18 has an outlet passage 69 opening inwardly on the upper chamber 56 and outwardly on a machined face 70 thereof. This outlet passage is connectable through a suitable fitting through coolant outlet manifold to the inlet of the coolant circulation pump in a conventional manner so that forced circulation of coolant through the cylinder head is provided.
In order to increase cooling efficiency in the critical combustion surface areas of the fire-face wall 12, a plurality of cooling spines 71 are disposed on the inner fire-face wall surface 12a thereof, which are distributed among the four sections of the lower chamber over surface area located between the exhaust branch passages 35–38 (or the exhaust port wall portions 41–44) and extending radially outwardly therefrom. Additional web members are provided in the lower chamber for supporting the chamber wall 45 including a pair of radially directed members 72 disposed in sections 58 and 60 and a radially directed rib 74 in section 61 which intersects wall 16 and includes an opening 75 for permitting the equalization of coolant flow. Also included is a radial member 76 extending from a diagonal boss 78 which is located in section 59 and encloses a cylinder test passage 79.
The foregoing describes in substantial detail certain features of the preferred embodiment disclosed in U.S. Pat. No. 4,860,700, which are similar in construction to the arrangement of the previously mentioned U.S. Pat. No. 3,377,996. In accordance with the disclosure of U.S. Pat. No. 4,860,700 over U.S. Pat. No. 3,377,996, certain structural changes were made thereto.
As can be seen in FIG. 5 (as compared with FIG. 6 of U.S. Pat. No. 3,377,996), the partition walls 46 were modified. The change was such that at the connections of their inner ends with their respective exhaust port wall portions 41–44, the partition walls 46 lie tangent to the exhaust port wall portions 41–44 on the sides thereof facing toward the outlet sections 58, 60 of the lower jacket chamber 55.
Preferably also, as shown, the outer ends of the partition walls 46 connect with adjacent ones of the stud bosses 22–29, specifically numbers 23, 24, 27 and 28, in a manner such that they also lie tangent to these stud bosses on their sides facing toward the inlet sections 59, 61 of the lower jacket chamber. These modifications result in more nearly, though not precisely, radial orientations of the partition walls 46 as compared to the essentially parallel orientations of the prior arrangement of U.S. Pat. No. 3,377,996.
In operation in an engine having a cylinder head with coolant jacket as described, the manner and direction of coolant flow is essentially as described in U.S. Pat. No. 3,377,996. Thus, by far, the major portion of the coolant enters the cylinder head through coolant inlet ports 66 in the inlet sections 59 and 61 of the lower jacket chamber 55. The closely spaced partition walls 45 direct the coolant inwardly toward the center of the head and it sweeps completely around the peripheries of exhaust passage wall portions 41–44, passes into outlet sections 58 and 60 and out of the lower chamber through outlet ports 64 leading to the upper jacket chamber 56.
According to the disclosure of U.S. Pat. No. 4,860,700, the velocity of the coolant is accelerated due to the constricted passages between the exhaust port wall portions 41–44 as well as between the sleeve defining wall portion 32 and the various branch passage walls; the cooling spines 71, located between the branch passage walls, further accelerate the flow and increase turbulence to obtain a high degree of scrubbing action and very efficient cooling; and the small inlet openings 68, provided in sections 58 and 60, pass a very small percentage of coolant flow into the head and serve to prevent the existence of hot spots in the connected cylinder liner.
Upon passing upwardly through coolant by-pass ports 64 into the upper chamber, the coolant sweeps over the exhaust passage defining wall 47 and around the outer peripheries of the sleeve defining wall portion 32 and valve guide wall portions 48 before leaving the upper chamber through outlet passage 69. A restricted flow of coolant is also permitted to pass directly from chamber 59 through the coolant by-pass ports 65 in partition wall 45 and into the upper jacket chamber. The coolant by-pass ports 65 allow removal of coolant from the adjacent portions of the cylinder head when the engine cooling system is drained. Likewise, a small flow of coolant is permitted to pass from section 61 of the lower jacket chamber through restrictive openings 80 in passages 54 to cool the struts 51 and 52 as well as prevent stagnation in the upper chamber.
According to U.S. Pat. No. 4,860,700, the modified tangential positioning of the partition walls 46 avoids the creation of stagnant pockets of coolant, particularly on the outlet section sides of the partition walls between the exhaust port wall portions 41–44 and the outer peripheral sidewall 16, wherein the coolant flow entering the outlet sections from the passages 62 is encouraged to flow directly along the surfaces of the partition walls 46, cooling the metal surfaces by its scrubbing action and avoiding hot spots which might be caused by stagnation if the coolant was directed past recesses or pockets in the jacket construction.
In similar fashion according to U.S. Pat. No. 4,860,700, the tangent connection of the partition walls 46 with the stud bosses 23, 24, 27, 28 minimizes the formation of pockets on the inlet section sides of the partition walls and improves the access of coolant to the wall areas adjacent to the coolant inlet ports 66 located toward the edges of the inlet sections, wherein the tangential web arrangement is believed, according to U.S. Pat. No. 4,860,700, to improve the cooling action of the flowing coolant on both the inlet and outlet sides of the partition walls.
While a diesel engine configured according to the disclosure of said U.S. Pat. No. 4,860,700 has exceptionally excellent performance characteristics, as for example the two-stroke, medium speed, 2000 to 5000 HP range General Motors Corporation Electromotive Division 645 and 710 diesel engines, modifications thereto would be desirable to improve valve seat cooling and increase the fire-face wall heat transfer. If such modifications could be achieved, expected would be improved cylinder head reliability due to lower metal operating temperatures and resultant lower thermal distortion and stresses, a well as improved valve seating and reliability due to reduced valve seat temperature and a more uniform valve seat temperature.
More particularly, what is needed in the art is to address the following five problem issues associated with the foregoing disclosure contained in U.S. Pat. No. 4,860,700, to wit: (1) the partition walls 46 not providing coolant flow as described above; (2) the spines 71 not performing heat exchange as described above; (3) need for improved heat transfer to the coolant of the fire-face wall 12; (4) need to reduce coolant by-pass through the coolant by-pass ports 65 so as to increase coolant circulation in the vicinity of the exhaust port wall portions 41–44 and the sleeve defining wall portion 32; and (5) need to increase structural stiffness at the radial rib 74.